Method and system for aviation navigation

ABSTRACT

A system operates to guide an aircraft to or along a route designed to maintain the aircraft within a safe glide distance of an acceptable emergency landing area. The system uses a database of emergency landing areas with glide characteristics of an aircraft to determine a route that minimizes travel time or other specified parameter, while keeping the aircraft within a safe glide distance of a landing area in the database meeting the landing requirements for the aircraft.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority pursuant to 35 U.S.C. §119(e) to U.S.provisional application Ser. No. 60/727,637, filed Oct. 17, 2005, whichapplication is specifically incorporated herein, in its entirety, byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to computer-aided aircraft navigationmethods and systems employing such methods.

2. Description of Related Art

Currently, aircraft pilots, particularly pilots of small aircraft suchas “VFR” aircraft, are permitted significant latitude in choice offlight path and altitude between the origin and destination of a givenflight. At the same time, small aircraft are relatively prone to enginefailures that require emergency landing under no power. In addition,fuel system malfunctions or leaks, and fuel mismanagement ormiscalculations, can impact aircraft of any size. Under the properweather and landing conditions, small aircraft are designed to becontrollable without engine power, and can be glided to a safe landing.Even larger aircraft may be capable of making a survivable landing aftersuffering a loss or reduction of power. To accomplish a safe landing, itis necessary that an acceptable landing area be available within adefined maximum glide distance of the location where engine failureoccurs. The maximum glide distance depends mainly on the glidecharacteristics of the aircraft, the aircraft altitude when enginefailure occurs, aircraft airspeed and altitude at all points of thedescent, and altitude, temperature, wind speed and direction.

Under emergency or non-emergency conditions, selection of the bestacceptable emergency landing area is rarely trivial, and mistakes can befatal. The calculation of maximum glide distance is prone to error, andthe availability and location of acceptable emergency landing areas isoften unknown. The identification of an acceptable landing area can besignificantly complicated if the aircraft is in, or above, conditionsthat obscure or limit the pilot's ability to view the ground, if theaircraft is flying at night, or if the aircraft is over rough terrain.Similarly, if the aircraft is over an area with numerous roads, some ofwhich are acceptable for landing and others are not (for reasons such aspower lines crossing the road, insufficient road width and obstacleclearance, etc), or in other conditions, the pilot may incorrectlyidentify a landing target only to determine, when he is too close to theground to pick another target, that the intended landing target is notin fact safe. Current navigation equipment does not adequately assistaircraft pilots in the selection of emergency areas, in the event ofengine failure.

Furthermore, a pilot in an emergency landing situation often is in theposition of being able to make only one approach to the landing site. Ifthe pilot picks the wrong glideslope, approach speed, or other aspectsof the approach, the pilot may overshoot or undershoot the target. Whilethe likelihood of such a “miss” is increased in poor visibility orsignificant wind conditions, it is present even in clear weather aspilots rarely practice “power-off” landings all the way from a cruisealtitude to the ground.

In addition, prudent flight planning would plot a course and altitude soas to keep the aircraft, to the extent possible, within a safe glidingdistance of an emergency landing area at all times during the flight.However, the information gathering and calculation required to performthis task are too burdensome to permit detailed consideration ofemergency landing in flight planning. Pilots therefore missopportunities to navigating aircraft so as to minimize the likelihoodthat an emergency landing will not be successful. It would be desirable,therefore, to provide a tool whereby the chances of a successfulemergency landing may be improved via prudent navigation.

SUMMARY OF THE INVENTION

The present invention provides a method and system whereby pilots maytake greater account of emergency landing areas in the navigation ofaircraft, including both in pre-flight planning and in-flightmodifications. A system according to the invention may operate tonavigate aircraft along a flight path that minimizes flight time or fuelconsumption, while keeping the aircraft within a safe gliding distanceof at least one emergency landing area at all times during the flight,or during some specified percentage of flight time. The system may, inthe alternative or in addition, keep the aircraft within a defineddistance of other locations along the route, or plan a route to maintainthe plane within a glide distance of emergency landing areas, andprohibited, restricted, or otherwise limited airspace.

Emergency landing areas may be classified according to theirdesirability for emergency landing. More desirable areas, such asoperating or abandoned airstrips, may be given a higher classification,and less desirable areas, such as open fields or roadways, may be givena lower classification. A system according to the invention can beconfigured, for example, to select only landing areas exceeding somethreshold of classification for use as potential emergency landingareas. In the alternative, the system may select landing areas in apriority order determined at least in part from their respectiveclassifications.

The system may also gather aircraft-specific information for use innavigation, including glide characteristics, such as the rate of descentat various airspeeds and in various aircraft gear, flap, and otherconfigurations and varying payload weights for various models ofaircraft, and the range of operable airspeeds under glide conditions. Inaddition, the aircraft landing requirements may also be gathered, suchas the minimum landing strip length needed for landing, the minimumobstacle clearance required on approach, and the minimum width requiredto accommodate the wingspan. Optionally, aircraft fuel consumptioncharacteristics may be gathered and maintained for use in planningfuel-efficient routes. The system should also be provided with currentweather conditions, especially current wind speed and direction at thecurrent aircraft location and at point on or near an anticipated flightpath. These information aspects of the navigational system may bemaintained and stored on a regional or national basis so as to beavailable generally to all users of the system.

Prior to beginning a flight, a pilot may access the system to request asafe flight plan between a starting location, or origin, and adestination. Optionally, the pilot may specify other desired parameters,for example, such as a desired margin of error for safe landing, apercentage of total flight time during which the aircraft should be keptwithin a glide range of an emergency landing area of specified class, adesired minimum or maximum cruising altitude, whether a route should bebased on minimum flight time or minimum fuel consumption, and/or customglide characteristics for a particular aircraft.

A computer may then be used to calculate a route, include both directionand altitude, that maintains the desired level of proximity to emergencylanding areas while achieving minimum flight time or fuel consumption.Various error minimization algorithms are known in the art, and anysuitable algorithm may be employed. A suitable algorithm should takeinto account the pertinent aforementioned parameters to determine aroute between the origin and destination that minimizes travel time orfuel consumption, given the constraint that the aircraft remain within aglide distance of an emergency landing area for a specified percentage(e.g., 100% or 90%) of the flight.

Part of this calculation may involve selecting the acceptable landingareas between the origin and destination, using the database ofemergency landing areas, the aircraft-specific landing requirements, theglide characteristics of the aircraft under the anticipated payloadconditions, and the projected weather conditions on emergency approachto and during landing at the target landing area at a projected time ofthe in-flight power loss. In an embodiment of the invention, thesuitable landing areas that are located most closely along a straightline, optimal route may be located, and the route adjusted to maintain asafe glide distance from these sites. If the desired percentage of theroute is not within a glide distance of a landing area, then additionallanding areas may be sought to cover portions of the route, or theaircraft altitude may be increased, or some combination of theforegoing.

In an alternative embodiment of the invention, or in addition, theplanning software may attempt to keep the aircraft within areas of radarcoverage, within areas that air traffic control may provide services,within areas of radio coverage, within published airways, withinaccepted VFR or IFR routes, or with some combination of the foregoing.Other selection methods may also be suitable.

As a preflight planning system, the foregoing may be entirelyground-based. For example, it may be operated on a network accessiblevia an Internet website. In an embodiment of the invention, some portionof the system may be placed in a portable device for in-flight use. Thispermits use of the system for in-flight travel modifications.

In addition, or in the alternative, an “emergency” function may beprovided to an in-flight system such as a GPS navigation system.Activating the emergency system will cause the system to calculate oneor more acceptable emergency landing areas, given the current aircraftlocation and altitude, under current or anticipated weather conditions.If no landing areas of the highest classification are available, thesystem may find the nearest landing area of the highest availableclassification, and direct the pilot toward that location. Optionally,the navigation system guides the pilot to the landing area by providingcourse vectors and required minimum and maximum descent rates. Thesystem optionally warns the pilot how long the best glide speed must bemaintained, sends an emergency signal optionally containing aircraftcoordinates, or optionally tunes the radio to appropriate frequenciesfor emergency reporting or the destination airstrip. The systemoptionally integrates with an autopilot and/or autothrottle to provideaircraft control. The system optionally integrates with a glideslopeinstrument or provides a digital simulated glideslope, that the pilotmay follow in the same manner that pilots are using to following on aprecision landing approach.

A more complete understanding of the method and system for aircraftnavigation will be afforded to those skilled in the art, as well as arealization of additional advantages and objects thereof, by aconsideration of the following detailed description of the preferredembodiment. Reference will be made to the appended sheets of drawingswhich will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing aspects of an aircraft navigationsystem according to an embodiment of the invention.

FIG. 2 is a flow diagram showing exemplary steps of a method accordingto an embodiment of the invention.

FIG. 3 is a flow chart showing exemplary steps of an emergencynavigation method according to an embodiment of the invention.

FIG. 4 is a schematic diagram showing aspects of an exemplary emergencynavigation system according to an embodiment of the invention.

FIG. 5 is a schematic diagram showing aspects of an exemplaryinformation updating system according to an embodiment of the invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

In the detailed description that follows, like element numerals are usedto indicate like elements appearing in one or more of the figures. FIG.1 is a schematic diagram showing aspects of an aircraft navigationsystem 100 according to an embodiment of the invention. It should beappreciated that the invention may be implemented on any suitablecomputing platform.

In an embodiment of the invention, navigation system 100 comprises acomputer 102 operatively associated with a database 104. Database 104may contain data describing the location and characteristics ofemergency landing area. Data concerning landing areas may be gathered inadvance using various manual or semi-automatic data. Such data mayinclude the geographic location of the landing area, elevation, lengthand orientation of landing strips, surface type (i.e., pavement, gravel,grass, water), use type (airstrip, abandoned airstrip, roadway, field,lake, etc.), and any other information useful for selecting or using alanding area. In an embodiment of the invention, topological maps may bescanned to select candidate landing areas, which are then screened toselect useful landing areas for inclusion in the database. Each landingarea may be assigned a classification to indicate its desirability as alanding area, for example, class ‘A,’ class ‘B,’ etc. Once the databasehas been populated with such data, it should be periodically checked andupdated as needed to maintain accurate information. Generally, however,data concerning emergency landing areas should not be expected to changerapidly. Database 104 may also store completed flight plans betweendefined destination, for re-use or modification in the future. Database104 may be constructed and operated in any suitable manner known in theart of computer databases.

Computer 102 may comprise a memory 105 holding program instructions foroperating the system to perform steps of the invention, describedhereinbelow. The computer may also be provided with a local userinterface 103 configured for accessing and maintaining database 104, andfor operating, configuring, or maintaining one or more programs forperforming aviation navigation as disclosed herein. Computer 102 may beoperated as a stand-alone system with all activity performed locally. Inan embodiment of the invention, however, computer 102 may be connectedvia a network 106, such as a wide-area or local-area network, to aplurality of client computers, one client 108 of many shown.

It should be understood that a “computer,” “computer module,” or“computer circuit” as used herein should be taken to mean any operablecombination of hardware, software, or firmware for performing acomputing function. For example, a computer may comprise ageneral-purpose computer comprising hardware, a low-level operatingsystem in firmware, and applications and a high-level operating systemin software stored in non-volatile memory. For further example, acomputer may comprise special purpose hardware and firmware, or somecombination of firmware and software. Instructions for performingactions as disclosed herein may be implemented in a computer asfirmware, hardware, software, or as any operable combination offirmware, hardware, or software. Various operable combinations should beapparent to one of ordinary skill, in light of the present disclosure.

Client 108 and host 102 may communicate in any suitable fashion as knownin computing networking. In an embodiment of the invention,communication may occur primarily through World Wide Web pages. Client108 may be used to fill information in forms provided from host 102,which is then used in flight planning. Completed flight plans may beaccessed via a Web page served from the host. In an alternativeembodiment, client 108 and host 102 may establish any othercommunication link, and client 108 may be used to operate a clientinterface that exchanges information with the host 102.

Client 108 may be connected to an output device 110, such as, forexample, a display screen, printer, or removable memory port. The outputdevice may be used to output information defining a flight plan for usein flight. In an embodiment of the invention, a printed flight plan 112is prepared. In the alternative, or in addition, the flight plan may bewritten to a portable memory 114, such as a USB-enabled non-volatilememory chip, an optical media disk, or a magnetic media disk. Theportable memory may be connected to a navigation system in the aircraft,which, in turn, may generate a navigational display or audio outputduring the flight to guide the pilot along the generated flight path.For example, a navigation system may generate audible commands and a mapshowing the path and position of the aircraft for guiding the pilot tothe planned destination along a flight path recorded on memory 114. Inthe alternative, computer 108 may be an on-board system in communicationvia a wireless link to host 102, and generate navigational audio and/orvisual output directly in the aircraft cabin. In yet another alternativeembodiment, host 102 and client 108 are integrated with database 104 inan on board computer system.

Software comprising instructions for performing steps of the methodsdescribed herein may be encoded in a computer-readable medium 107, suchas a magnetic disk or tape, optical disk, or memory chip. When connectedto computer 102, these instructions may be read into an operating memoryof the computer, enabling performance of the methods described herein.Medium 107 may be a portable medium, may be permanently installed withina housing of the computer, or otherwise configured in any suitablefashion.

System 100 may be used to perform a method of navigating an aircraft asshown in FIG. 2. At an initial step, the system receives the desiredparameters for a flight plan. These parameters may include a desiredorigin (i.e., starting location) and destination for the flight. Theorigin and destination may be defined in any suitable fashion, forexample by FAA standard 3-letter airport codes, latitude/longitude ofthe origin or destination, street address, or by any other suitabledescription. Other flight parameters to be specified by a pilot orflight planner, and received by system 100, may include a departure timeand a percentage or percentages of time to remain within a safe glideradius of an emergency landing area. Different percentages may bespecified to obtain different flight plans; for example, a pilot mayspecify a first plan using parameters of 90% of time within glide rangeof a Class ‘A’ landing area (e.g., airport or abandoned airstrip) and10% of time within glide range of the best available alternative landingarea, leading to a first flight plan. Specifying different parameters,for example, 50% of time within a glide range of a Class ‘A’ landingarea and 50% of time within a Class “R” (e.g., paved roadway) landingarea may lead to a very different flight plan for the same flight.

Other parameters that may be specified, and that may be important in theselection or use of a landing area, may also be specified. Suchparameters may include, for example, the type or model of aircraft thatwill be used in the flight. In an embodiment of the invention, glidecharacteristics and landing requirements for various models of aircraftunder different conditions may be maintained in the system database toease the chore of configuring the system for a particular aircraft andflight. In the alternative, or in addition, glide characteristics andlanding requirements may be entered manually. This information mayinclude, for example, the range of glide speeds the plane is capable ofunder various conditions, such with or without landing gear extended,etc, the best glide speed, the rate of descent at different glide speedsand payloads, the maximum cruising altitude, maximum airspeed, and soforth. Other parameters may include the amount of fuel on board, theweight of other payload on board, acceptable terrain for landing,wingspan, minimum landing length needed, or other pertinent data. In anembodiment of the invention, a flight planner may also specify whetherthe flight plan should be optimized for shortest possible time, leastpossible fuel consumption, or any other desired parameter. Flightparameters, in general, may be manually entered or selected from adatabase based on other criteria entered into the system.

After flight parameters have been sufficiently specified, a systemcomputer may begin processing the received data to determine a flightpath and select landing areas, as shown by steps 204 and 206. Theseprocesses may be performed concurrently or iteratively to achieve aflight plan that achieves the required parameters for the flight.

Various algorithms may be used. For example, the computer may begin byselecting a straight line path between the origin and destination,locating emergency landing areas within a defined distance of the path,re-defining a plan within a glide range of the emergency landing areas,testing to see if the flight parameters are satisfied, and if not,locating additional landing areas and continuing this process until allflight conditions are satisfied. In determining a flight path betweenthe origin and destination, the flight path may be calculated tomaintain the aircraft within glide range of least one acceptableemergency landing area along different defined portions of the flightpath, based on the glide characteristics and locations of acceptableemergency landing areas generally between the origin and destination. Asused herein, “generally between the origin and destination” should betaken to mean “within a glide range of a flight path between the originand destination.”

In an embodiment of the invention, the flight path may be defined firstand best available emergency landing areas selected along the route. Inthis embodiment, a pilot may be permitted to define a flight path, withthe computer merely locating the best available emergency landing areas,and indicating the portions of the flight path that are not within aglide range of a landing area. Still another approach is to permit apilot to manually define an envelope for the flight path, and thendefining an optimal flight path within the defined envelope via aniterative process. Landing areas may be selected based on the aircraftemergency landing requirements, landing preferences indicated by apilot, and the characteristics of the emergency landing areas asrecorded in the database. Once the locations of suitable landing areashave been identified between the origin and destination, defining anoptimal path between the location and destination may be performed byany suitable path-finding algorithm.

Once a flight plan meeting the specified criteria has been defined, itmay be presented to the user at step 208, for example by preparation ofa written map and plan that may be printed out or displayed on a screen.The flight planner may inspect the plan and, if the plan is not to herliking, adjust the criteria to define an alternative flight plan. Once aflight plan has been accepted by the user, the plan may be saved forfuture reference at step 210. As previously noted, a flight plan may beoutput in electronic form, for use by an on-board navigation system. Atstep 212, an onboard navigation system may use the flight plan todevelop and provide vectors to the pilot, to guide and maintain theaircraft along the planned flight path.

In an embodiment of the invention, a pilot is guided to an emergencylanding area at any point during a flight, such as when engine failureor other equipment failure occurs, or for training purposes. FIG. 3 is aflow chart showing exemplary steps of an emergency navigation method 300according to the invention. At step 302, flight status is determinedwhen the method is activated. The method may be activated, for example,when a pilot selects an emergency button or other indicator, powerfailure is sensed, or any other event occurs that the system has beenconfigured to recognize. Determination of flight status may comprise,for example, receiving a current altitude, location, glidecharacteristics and landing requirements for an aircraft. Generally, theglide characteristics and landing requirements for an aircraft should bemaintained in an on-board memory of the emergency system. The currentlocation and altitude may be determined from a GPS device or otherlocating system. Other parameters may also be received, for example thecurrent weather conditions, such as average wind speed and direction,fuel level, whether or not the landing gear is retracted, and any otherparameter useful for guiding the aircraft to an emergency landing area.

At step 304, an on-board computer may select a nearest acceptablelanding area from a database of landing areas meeting the landingrequirements and within glide range. Once the current equipment status,wind speed and direction, and altitude are known, the glide radius invarious directions may be calculated. The system may select any numberof emergency landing areas located in the glide radius, and prioritizethem according to suitability for an emergency landing, distance fromcurrent location, and pilot preferences for landing areas, if any. Oneor more of the highest-priority emergency landing areas may be selected.Selection may occur automatically or semi-automatically. For example, adefault landing area may be selected by the computer and presented tothe pilot with alternative landing areas, and the pilot may select anyacceptable landing area within the glide radius.

Once the landing area is selected, the emergency navigation system mayprovide a location and description of the nearest acceptable landingarea. Subsequently, the navigation system may provide vectors andrequired descent speed to guide the pilot to the landing area, includingcourse corrections as necessary to keep the aircraft on an optimal glidepath. The navigation system may also provide a signal to display toconfirm that the aircraft is maintaining a proper glide path and course.Optionally, via a connection to an autopilot system, the emergencynavigation system may fly the plane to the emergency landing area for aslong as the pilot desires.

In an embodiment of the invention, the navigation system may broadcastan emergency signal comprising current coordinates and location of theselected landing area. This may be useful to alert other pilots in thevicinity and the airstrip controllers, if any, that a plane is glidingin for a landing under emergency conditions.

Method 300 may be implemented by any suitable onboard system. FIG. 4 isa schematic diagram showing aspects of an exemplary emergency navigationsystem 400 according to the invention. System 400 comprises a computer402 having a memory 405 holding instructions for performing stepsaccording to the invention. The computer is operatively associated witha database 404 of emergency landing areas. The database may be updatedperiodically via a wireless connection or other media update process.Database 404 may also hold information describing the glidecharacteristics of the aircraft, and its emergency landing requirements.Software comprising instructions for performing steps of the methodsdescribed herein may be encoded in a computer-readable medium 407, suchas a magnetic disk or tape, optical disk, or memory chip. When connectedto computer 402, these instructions may be read into an operating memoryof the computer, enabling performance of the methods described herein.

Computer 402 may be connected to a display device 406, used to providevisual and/or audible guidance to the pilot, to guide the pilot towardsa selected emergency landing area. Computer 402 may also receive inputfrom one or more sensors 410 associated with the aircraft 412, forexample, airspeed indicators and fuel level sensors. The computer mayalso receive data via one or more antennae 414. For example, thecomputer may be able to receive weather information regarding theanticipated glide path via a radio configured to receive, and optionallyto send, data to transmitter/receiver for a weather monitoring service.

Computer 402 may further be connected to an autopilot controller 408 forautomatically guiding the plane to the emergency landing area.Optionally, the computer may send the autopilot information formaintaining the aircraft 412 on the proper glide path needed to safelyland at the selected emergency landing area.

It may be advantageous to periodically update data available to aportable navigation system such as described above. Updating may beaccomplished, for example, via a ground based data system 500, as shownin FIG. 5. System 500 comprises a computer 502 through which a humanoperator, or an automatic software agent, may obtain and verify updatedor new information regarding parameters used in navigation. Aspreviously described, these parameters may include information regardingemergency landing areas, weather data, or other information that tendsto change with time. The administrative computer may transmit updatedinformation via a transmitter 504 to a navigation system 506 located inan aircraft 508. In the alternative, all or a portion of the navigationsystem may be located in a ground-based system, such as system 100described above. Upon receiving the new or updated information, thenavigation system updates associated database areas, and the new orupdated information may thereafter be used in navigation flight planningor in emergency navigation.

Having thus described various embodiments of the system and method foraircraft navigation, it should be apparent to those skilled in the artthat certain advantages of the within system have been achieved. Itshould also be appreciated that various modifications, adaptations, andalternative embodiments thereof may be made within the scope and spiritof the present invention, which is not limited to the describedembodiments. It should be understood that “the invention” as used hereinshould be taken to mean “an embodiment of at least one of the inventionsdescribed herein,” and thus may be taken as including the plural“inventions” and as not requiring any particular aspect or embodiment ofthe inventions disclosed.

1. A method for defining a flight path for an aircraft based on glidecharacteristics, the method performing computer-implemented operationscomprising: receiving flight parameters comprising an origin, adestination, glide characteristics for an aircraft, and emergencylanding area preferences including criteria for selection of acceptableemergency landing areas; and determining a flight path between theorigin and destination, the flight path calculated to maintain theaircraft within glide range of selected acceptable emergency landingareas located within a glide range indicated in the received glidecharacteristics and matching the emergency landing area preferences,wherein at least one of the selected acceptable emergency landing areasis not part of an airport; wherein the selected acceptable emergencylanding areas are chosen based at least in part on landing areaclassifications from a database of emergency landing areas and thereceived emergency landing area preferences.
 2. The method of claim 1,wherein the selected acceptable emergency landing areas comprise aplurality of landing areas each meeting defined acceptable landingcriteria for the aircraft.
 3. The method of claim 2, wherein the definedacceptable landing criteria comprises one or more of terrainrestrictions, landing area classifications, and required minimum rolldistance.
 4. The method of claim 3, wherein the selected acceptableemergency landing areas are chosen according to a priority orderdetermined at least in part from their respective classifications. 5.The method of claim 1, further comprising selecting the selectedacceptable emergency landing areas from landing areas exceeding adefined threshold of classification.
 6. The method of claim 1, whereinthe determining step further comprises calculating the flight path tominimize at least one of travel time and fuel consumption between theorigin and destination.
 7. The method of claim 1, wherein the glidecharacteristics comprise a best glide speed and a descent rate at thebest glide speed.
 8. The method of claim 1, wherein the glidecharacteristics comprise a glide speed range and a corresponding descentrate range.
 9. The method of claim 1, wherein the determining stepfurther comprises calculating the flight path using wind speed and winddirection data.
 10. The method of claim 1, further comprising providingflight vectors during the flight to maintain the aircraft on thedetermined flight path.
 11. The method of claim 1, further comprisingperiodically updating information pertaining to the emergency landingareas.
 12. The method of claim 1, wherein the determining is performedby a computer system comprising computer hardware.
 13. A system fordefining a flight path for an aircraft, the system comprising a computeroperatively associated with a memory, the memory holding instructionsfor: receiving at least glide characteristics for an aircraft andemergency landing area preferences including a first percentageindicating a percentage of a flight path in which the aircraft should bewithin a glide range of any emergency landing area having a firstlanding area classification and a second percentage indicating apercentage of the flight path in which the aircraft may be within theglide range of any emergency landing area having a second landing areaclassification, wherein the first landing area classification includesairports and the second landing area classification does not includeairports; and determining a flight path between an origin and adestination, the flight path calculated to maintain the aircraft withinglide range of selected acceptable emergency landing areas from adatabase of emergency landing areas, including the requirement that theaircraft is within the glide range of emergency landing areas having thefirst landing area classification for at least the first percentage ofthe flight path and the aircraft is within the glide range of onlyemergency landing areas having the second landing area classificationfor no more than the second percentage of the flight path.
 14. Thesystem of claim 13, wherein the selected acceptable emergency landingareas comprise a plurality of landing areas each meeting definedacceptable landing criteria for the aircraft.
 15. The system of claim 14wherein the defined acceptable landing criteria comprises terrainrestrictions, landing area classifications, and required minimum rolldistance.
 16. The system of claim 13, the memory further holdinginstructions for selecting the selected acceptable emergency landingareas from landing areas exceeding a defined threshold ofclassification.
 17. The system of claim 16, the memory further holdinginstructions for calculating the flight path to minimize fuelconsumption between the origin and the destination.
 18. The system ofclaim 13, the memory further holding instructions for calculating theflight path to minimize travel time between the origin and thedestination.
 19. The system of claim 13, the memory further holdinginstructions for calculating the flight path using wind speed and winddirection data.
 20. The system of claim 13, the memory further holdinginstructions for providing flight vectors during the flight to maintainthe aircraft on the determined flight path.
 21. A tangiblecomputer-readable medium having instructions stored thereon configuredfor execution on a computing device in order to cause the computingdevice to: receive flight parameters comprising an origin, adestination, a maximum cruising altitude, a maximum airspeed, glidecharacteristics for an aircraft, and emergency landing area preferencesincluding criteria for selection of acceptable emergency landing areas;and determine a flight path between the origin and destination, theflight path calculated to maintain the aircraft within a glide rangeindicated in the received glide characteristics of selected acceptableemergency landing areas matching the emergency landing area preferencesalong flight path, wherein at least one of the selected acceptableemergency landing areas is not part of an airport; wherein the at leastone acceptable emergency landing area is selected based at least in parton a landing area classification from a database of emergency landingareas and the received emergency landing area preferences.
 22. Thecomputer-readable medium of claim 21, wherein the selected acceptableemergency landing areas comprise a plurality of landing areas eachmeeting defined acceptable landing criteria for the aircraft.
 23. Thecomputer-readable medium of claim 22, wherein the defined acceptablelanding criteria comprise terrain restrictions, landing areaclassifications, and required minimum roll distance.
 24. Thecomputer-readable medium of claim 21, further holding instructions forselecting the selected acceptable emergency landing areas from landingareas exceeding a defined threshold of classification.
 25. Thecomputer-readable medium of claim 21, further holding instructionsoperative to calculate the flight path to minimize at least one oftravel time and fuel consumption between the origin and the destination.26. The computer-readable medium of claim 21, further holdinginstructions operative to calculate the flight path to minimize fuelconsumption between the origin and the destination.
 27. Thecomputer-readable medium of claim 21, further holding instructionsoperative to calculate the flight path using wind speed and winddirection data.
 28. The computer-readable medium of claim 21, furtherholding instructions operative to provide flight vectors during theflight to maintain the aircraft on the determined flight path.